(07-22-2013, 03:26 PM)montehotbike12 Wrote: ... As you suggested I checked some other nights and the leak rate seems low. You are correct! ...I really like the Quattro FX. I find it to be far superior in leak reduction, compared to any other mask. It's obviously working for you.
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(07-22-2013, 08:44 PM)DreamDiver Wrote:
Dreamdiver: I lowered my setting from 9 back to 8 last PM (kept upper setting at 16)....just to see if it was the increased pressure of 9 or the tennis ball in the t shirt that did the trick....so it is obvious that I was having some significant positional apneas. Last nights AHI was 2.79 with only minimal OA's and mostly hypopneas....so I am going to take your advice and bump the lower number back up to try to get rid of the hypopneas.
07-23-2013, 10:16 AM
(07-23-2013, 09:39 AM)montehotbike12 Wrote: Dreamdiver: I lowered my setting from 9 back to 8 last PM (kept upper setting at 16)....just to see if it was the increased pressure of 9 or the tennis ball in the t shirt that did the trick....so it is obvious that I was having some significant positional apneas. Last nights AHI was 2.79 with only minimal OA's and mostly hypopneas....so I am going to take your advice and bump the lower number back up to try to get rid of the hypopneas.Hi Monte,
It's really a good idea to not move the dials around night to night when self titrating, but rather to stay put for several nights--especially when you're already at such a low AHI. Sleep hygiene is not the only thing that plays a part in your AHI. It also depends on what you ate during the day, how much alcohol you have had to drink, how much water you have had, how much physical exercise, etc. There are so many variables during the day that affect your AHI, that it's best to have an average from multiple nights at the same pressure regime. Patience will reward you. Consider: You're already well below 5, which is considered well-treated according to medicare. Anything else is gravy. If this were my machine, I would pick a lower and upper setting and stick with them for a while, and then get an average for those nights and make changes based on more these more-sound criteria. Just a thought...
07-23-2013, 04:03 PM
(07-23-2013, 10:16 AM)DreamDiver Wrote:(07-23-2013, 09:39 AM)montehotbike12 Wrote: Dreamdiver: I lowered my setting from 9 back to 8 last PM (kept upper setting at 16)....just to see if it was the increased pressure of 9 or the tennis ball in the t shirt that did the trick....so it is obvious that I was having some significant positional apneas. Last nights AHI was 2.79 with only minimal OA's and mostly hypopneas....so I am going to take your advice and bump the lower number back up to try to get rid of the hypopneas.Hi Monte,
Good points indeed. I just get carried away whenever I get a new gadget One thing I noticed is the more tired I am, the higher my AHI (and the more I snored before getting the CPAP). A few beers before bedtime will up the obstructives as well in my case.
In this article, Philips Respironics describes their "Non-Responsive Apnea/Hypopnea" algorithm. Basically, if the device detects apnea events, it will increase the pressure. However, if the events continue unabated after a 3 cmH2O increase in pressure, the machine treats the events as "non-responsive" and decreases the pressure to "stabilize the airway". I suspect ResMed devices do something similar.
In other words, if you have an auto pressure range lower limit that is far too low for your condition, it may be that your device never actually gets to a high enough pressure to treat your apneas!
Your pressure plots look suspiciously like the plots of the Non-Responsive behaviour plots.
(07-23-2013, 05:31 PM)RonWessels Wrote: In other words, if you have an auto pressure range lower limit that is far too low for your condition, it may be that your device never actually gets to a high enough pressure to treat your apneas!
That article is not well written. It starts by explaining that pressure should not be increased on patients who are experiencing central activity. In paragraph 3 it explains that the purpose of decreasing pressure in non-responsive apneas is to stabilize the airway which indicates that they lower pressure in response to some obstructive apneas. Then in paragraph 4 it says that if it sees that the events are obstructive, it overrides this logic and continues to increase pressure. Very confusing.
In paragraph 2 it says "Other algorithms limit the treatment of apnea events above a fixed pressure level, resulting in under-treated patients." What does that mean? The Respironics unit doesn't have an upper pressure limit!?
The way I read it (since it seems to be so open to interpretation) is that it only does the whole "up 3, then back off" thing when it thinks your apneas are central in nature as judged by snore and flow limitation.
Okay, I just realized what they meant. When they say they lower pressure to "stabilize the airway" they mean stabilizing it from an excessively high pressure during periods of central (non-responsive) apneas.
This is interesting because I thought pressure was never increased in the first place unless the flow limitation indicated an obstructive event. Otherwise what's the whole point of FOT and other such tests?
07-23-2013, 06:04 PM
I agree it could be clearer. It also doesn't mention the "pressure puffs" that are apparently used in the more modern machines to detect "clear airway" vs "obstructed" events.
However, as you mentioned, it uses flow limitation and snore results to determine whether to override the algorithm. If your pressure is woefully low, it may be that you bypass the initial indicators and go straight to a full obstructive event.
I was simply struck by the similarity in the pressure response of the Non-Responsive algorithm and the pressure plots posted in the initial article. Looking at them back when they were first posted, I could not understand why the machine stopped increasing the treatment pressure well before the apneas were treated. This may be the reason.
07-23-2013, 06:35 PM
This is the parent page, I think.
There are a number of satellite pages in the right-hand sidebar. Perhaps it makes more sense in context with the other pages?
If Non-Responsive Apnea/Hypopnea (NRAH) is the Phillips Respironics technique, this equivalent in ResMed is Forced Oscillation Technique (FOT).
I prefer the FOT method because it's less of a wake trigger for me. Half a cm pressure at 4.3Hz vs 3cm at 0.33 Hz... Quite a vast difference in approach.
It's different for everybody, though. NRAH works for plenty of users who prefer it. FOT works for the rest of us.
Found an interesting paper on FOT for central apnea detection:
The paper confirms that FOT prevents pressure increases when central apneas are detected. It superimposes a 1 cmH2O sine wave onto the flow at 4Hz. The flow resistance and presence of cardiac echo determines airway patency. If the event is central, pressure is not increased.
The Respironics approach seems to be to increase pressure regardless, up to 3 cmH20, then test. Please correct me if I misunderstood that.
Correction: It's maybe testing along the way while it's increasing pressure up to 3 cmH20, but the perceived result (to the patient) is an increase in pressure followed by a "test" resulting in a backing-off of pressure.
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